Year	Percent
1990	0.22
1991	0.35
1992	0.57
1993	0.89
1994	1.34
1995	1.9
1996	2.47
1997	2.9
1998	3.07
1999	2.97
2000	2.72
2001	2.42
2002	2.16
2003	1.96
2004	1.83
2005	1.75
2006	1.7
2007	1.66
2008	1.63
2009	1.55
2010	1.5
2011	1.43